ABSTRACT
DB-5 (60m) and CP-wax columns. GLC retention times for authentic samples of unsaturated C27 sterol derivatives were determined using capillary columns coated with D-1 (60m×0.25mm i.d.; 100% methylpolysiloxane; 0.1 µm film thickness, J&W Scientific, Folsom, CA), DB-55ms (30 or 60m×0.25 mm i.d.; 5% phenyl-95% methylsiloxane; 0.1µm film thickness; J&W); Stabilwax (30 or 60m×0.25mm i.d.; polyethylene glycol; 0.1µm fm thickness; Restek; Bellefonte, PA); CP-wax-57CB (25m×0.32mm i.d.; high-polarity polyethylene glycol; 0.2µm film thickness; Chrompack, Raritan, NJ). The GLC analyses for DB-1, DB-5, Stabilwax, and CP-wax were done isothermally on a Shimadzu GC-9A instrument. Either nitrogen or helium was used as a carrier gas, with a split ratio of 50:1 or 20:1. Injector and flame ionization detector temperatures were held at 250°C and 290°C, respectively. GC/MS analyses were done isothermally at 250°C on a Hewlett-Packard 5890A chromatograph. The temperature of the injector and GC/ MS interface was 270°C. Mass spectra (m/z 50-700) were measured on a ZABHF reversed-geometry double-focusing instrument at 0 eV and an electron impact ion source (200°C). The accelerating voltage was 8kV and the resolution was 1000 (10% valley).
